Messages in this thread | | | From | Daniel Phillips <> | Date | Sat, 25 Aug 2001 03:00:07 +0200 |
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On August 19, 2001 11:11 pm, Otto Wyss wrote: > I recently wrote some small files to the floppy disk and noticed almost nothing > happened immediately but after a certain time the floppy actually started > writing. So this action took more than 30 seconds instead just a few. This > remembered me of the elevator problem in the kernel. To transfer this example > into real live: A person who wants to take the elevator has to wait 8 hours > before the elevator even starts. While probably everyone agrees this is > ridiculous in real live astonishingly nobody complains about it in case of a disk.
My early flush patch, posted a month or so ago, takes care of this nicely. I'm just waiting for 2.5 to roll around to do some more work on it.
> [...] > Could anybody produce any real figures to prove/disprove my theory? Could > anybody benchmark the disk access for the 3 waiting times (0, 200ms 30sec) with > different loads?
Your theory is correct. I implemented the idea, took measurements, and found dramatic performance improvements under some loads, while getting worse on none. You can search lwn.net for a nice writeup by Jonathan Corbett.
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